svn commit - mysqldoc@docsrva: r9158 - in trunk: refman-5.1 refman-6.0

[jon]

Author: jstephens
Date: 2007-12-06 18:27:59 +0100 (Thu, 06 Dec 2007)
New Revision: 9158

Log:

COUNT() is not consistent on Cluster replication slaves (Thanks, Jonas!)



Modified:
   trunk/refman-5.1/mysql-cluster-limitations.xml
   trunk/refman-6.0/mysql-cluster-limitations.xml


Modified: trunk/refman-5.1/mysql-cluster-limitations.xml
===================================================================
--- trunk/refman-5.1/mysql-cluster-limitations.xml	2007-12-06 17:25:05 UTC (rev 9157)
+++ trunk/refman-5.1/mysql-cluster-limitations.xml	2007-12-06 17:27:59 UTC (rev 9158)
Changed blocks: 1, Lines Added: 25, Lines Deleted: 0; 1493 bytes

@@ -744,6 +744,31 @@
           </formalpara>
         </listitem>
 
+        <listitem>
+          <formalpara>
+
+            <title>Transactions and the <literal>COUNT()</literal> function</title>
+
+            <para>
+              When using MySQL Cluster Replication, it is not possible
+              to guarantee the transactional consistency of the
+              <literal>COUNT()</literal> function on the slave. In other
+              words, when performing on the master a series of
+              statements (<literal>INSERT</literal>,
+              <literal>DELETE</literal>, or both) that changes the
+              number of rows in a table within a single transaction,
+              executing <literal>SELECT COUNT(*) FROM
+              <replaceable>table</replaceable></literal> queries on the
+              slave may yield intermediate results. This is due to the
+              fact that <literal>SELECT COUNT(...)</literal> may perform
+              dirty reads, and is not a bug in the
+              <literal>NDB</literal> storage engine. (See Bug #31321 for
+              more information.)
+            </para>
+
+          </formalpara>
+        </listitem>
+
       </itemizedlist>
     </para>
 


Modified: trunk/refman-6.0/mysql-cluster-limitations.xml
===================================================================
--- trunk/refman-6.0/mysql-cluster-limitations.xml	2007-12-06 17:25:05 UTC (rev 9157)
+++ trunk/refman-6.0/mysql-cluster-limitations.xml	2007-12-06 17:27:59 UTC (rev 9158)
Changed blocks: 1, Lines Added: 25, Lines Deleted: 0; 1493 bytes

@@ -726,6 +726,31 @@
           </formalpara>
         </listitem>
 
+        <listitem>
+          <formalpara>
+
+            <title>Transactions and the <literal>COUNT()</literal> function</title>
+
+            <para>
+              When using MySQL Cluster Replication, it is not possible
+              to guarantee the transactional consistency of the
+              <literal>COUNT()</literal> function on the slave. In other
+              words, when performing on the master a series of
+              statements (<literal>INSERT</literal>,
+              <literal>DELETE</literal>, or both) that changes the
+              number of rows in a table within a single transaction,
+              executing <literal>SELECT COUNT(*) FROM
+              <replaceable>table</replaceable></literal> queries on the
+              slave may yield intermediate results. This is due to the
+              fact that <literal>SELECT COUNT(...)</literal> may perform
+              dirty reads, and is not a bug in the
+              <literal>NDB</literal> storage engine. (See Bug #31321 for
+              more information.)
+            </para>
+
+          </formalpara>
+        </listitem>
+
       </itemizedlist>
     </para>